CARBONIC-ANHYDRASE INHIBITORS .50. INTERACTION OF ISOZYME-I AND ISOZYME-II OF CARBONIC-ANHYDRASE WITH GE(IV) AND SB(III) DERIVATIVES

The interaction of carbonic anhydrase (CA) isozymes I and II with a se ries of Ge(IV) and Sb(III) derivatives containing among others arylsul fonylamido moieties in their molecule was investigated kinetically and spectrophotometrically, utilizing the native and Co(II)-substituted e nzymes. Depending on the substitution pattern at the germanium/antimon y and the sulfonamide nitrogen atoms, moderately active inhibitors as well as inactive compounds were detected. The active derivatives const itute a novel class of CA inhibitors that bind to the metal ion at the enzyme active site, as proved by changes in the electronic spectra of adducts of such inhibitors with Co(II)CA. Similarly to the prototypic al inhibitors of CAs, the aromatic/heterocyclic sulfonamides, the new inhibitors are of the non-competitive type when 4-nitrophenyl acetate is used as the substrate.